Compared to a regular microphone comprising a membrane and one backplate, a dual backplate microphone provides a performance increase on the same chip area. In a dual backplate microphone, a first capacitance between the membrane and the first backplate is measured and simultaneously a second capacitance between the membrane and the second backplate is measured. Compared to a single backplate microphone, the performance is increased by taking the difference between the measured capacitances. However, the performance of the microphone is highly dependent on the accuracy of the position of the membrane between the two backplates.
Methods are known to position the membrane between the two backplates precisely during manufacturing of a microphone. These methods optimize the design and the processing of the microphone. However, the precision that can be achieved during manufacturing is not accurate enough to fulfill the increasing demands concerning the specifications of microphones. Accordingly, there is a need to increase the precision of the positioning of the membrane between the two backplates in a dual backplate microphone.